期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：2
页码：340-344
DOI：10.1073/pnas.79.2.340
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Incubation of HeLa cell mRNA guanylyltransferase (GTP:mRNA guanylyltransferase, EC 2.7.7.50 ) with [alpha-32P]GTP and a divalent cation in the absence of an RNA acceptor results in the formation of a covalent enzyme-guanylate complex. The complex, after purification by phosphocellulose chromatography, can transfer its bound GMP moiety to pyrophosphate, regenerating GTP, or to the 5'-diphosphate end of poly(A), forming a cap structure G(5')pppA(pA)n. The GMP-polypeptide has a molecular weight of 65,000 and is stable to heating in the presence of sodium dodecyl sulfate. On the basis of the alkali-stable and acid-labile nature of the bond and its susceptibility to nucleophilic attack by hydroxylamine at low pH, the GMP-polypeptide linkage appears to be a phosphoamine bond. After digestion with trypsin, a single GMP-peptide was resolved by two dimensional electrophoresis and chromatography.
